A superior German fighter

Aozora · Jun 4, 2013

Shortround6 said:
In the engines designed in 1934-37 it was more a question of of capacity (displacement) vs rpm. Max boost was still pretty low in most engine.

The Kestrel used in the Bf 109 and Ju 87 prototypes used a max of 3.5lbs boost (1.24 ata?). Granted it was an in service engine and not a prototype.

R-R had Built the the 35 liter Condor from 1918 to 1926 or so ( and a diesel version in 1932) plus the Buzzard of 36.7 liters which they developed into the "R" racing engines. The Buzzard only weighed 1140lbs.

I don't know why R-R dropped to 27 liters for the Merlin but they certainly had experience and the capability to build larger engines. But Rolls had only been making aircraft engines for less than 20 years, the idea that the Merlin would still be in first line service 10-15 years in the future would probably have shocked the designers of the time. The Merlin being R-Rs 6th commercial (non racing) engine in under 20 years.

Design of the Merlin started in 1932 (original concepts envisaged an inverted vee as one possible layout) and there was the possibility that the 37 litre R series would be adapted to become the next big engine; as such 27 litres was a good "halfway house" between that and the the 21 litre Kestrel (later the Peregrine).

This was literal in that all R-R needed to do to go from 21 (Kestrel Bore: 5 in or 127 mm; Stroke: 5.5 in or 140 mm = 1,295.88 in³ (21.24 L)) to 27 litres was to increase the bore and stroke of each cylinder by roughly half an inch ie; Merlin: Bore: 5.4 in (137 mm) Stroke: 6.0 in (152 mm) 1,647 cu in (27 L): ditto to go up to 37 l Griffon Bore: 6 in (152.5 mm) Stroke: 6.6 in (167.6 mm) = 2,240 in3 (36.7 L). With their experience of the Rs Rolls-Royce knew they could get at least 1,000 hp out of a 27 l engine, with the added bonus that it would be reasonably compact for the power generated.

As it was Rolls-Royce decided to design a new 37 l engine to take advantage of the refinements made in the Merlin cf the R series and, in turn, added further refinements resulting in the Griffon.

With the Jumo 210 Junkers started their 21 series with a similar engine to the Kestrel; the Jumo 210 was Bore: 124 mm (4.88 in) Stroke: 136 mm (5.35 in) Displacement: 19.7 l (1,202 in³), but with the 211 the dimensions went up by roughly an inch to Bore: 150 mm (5.91 in)Stroke: 165 mm (6.5 in) = 34.99 l (2,135.2 in³)

GregP · Jun 6, 2013

Personally I like the Fw 187. But in the political atmosphere of the time, I don't think it would ever be adopted. The cirticisms leveled at it were lack of defensive aramament in the Destroyer role, not big enough for a radar fit in the fuselage, etc.

So despite being what would SEEM like a good candidate for a twin engine fighter, the people making the production desisions just didn't seem to want it.

However, the 12Y engine might have been a good idea and might have made a decent jump in performance while not using up the preferred DB engines. Not a bad choice, Tomo.

tomo pauk · Jun 6, 2013

Of course, I've posted about the 12Y because it could've added numbers to the German engines produced, not because it was some wunder engine in 1939/40. It might be interesting to contemplate the He-100 and/or He-112 with 12Y, again from production viewpoint.

Shortround6 · Jun 6, 2013

He-100 is a dead duck. The cowl was actually the engine mount. To change engines requires redesigning the plane from the firewall forward if not the firewall also, The Upper part of the cowl being sort of a double wall box beam (?) that the engine hung from.
Great for access to an inverted V-12. Throw away and start over for an upright V-12.
Now sort out the rest of the He-100s 'problems'.

He-112 is a maybe. But what do you have when you are done?

tomo pauk · Jun 7, 2013

Re-engining the He-100 for a different type of in-line should not be harder that re-engining the in-line-engined fighter into a radial-engined one, or vice versa. Maybe install the whole power egg from the Avia 135, ditching the retractable raditor.

With He-112/12Y I have the fighter that can decently perform (the historic He-112 was making 510 km/h with Jumo-210s), and my allies can actually buy it, without waiting for Bf-109.

tomo pauk · Jun 7, 2013

double post

Shortround6 · Jun 7, 2013

tomo pauk said:
Re-engining the He-100 for a different type of in-line should not be harder that re-engining the in-line-engined fighter into a radial-engined one,or vice versa.

On something like a P-36 to P-40 the engine mounts/bearers go to about the same attachment points at the firewall/bulkhead/frame and the loads are transferred to the structure ( longerons, truss framework, whatever). The fuselage covering/outer skin bears NO structural loads and is merely an aerodynamic covering for the engine ( and router of air for various needs).

The He 100 used something closer to this;

The outer covering is used (access hatches/doors aside) AS the engine mount. a more involved engineering problem.

It is possible (most anything is possible) but is it practical. Main stress attachments have to shift from the top/upper sides to the bottom/lower sides of the fuselage at the firewall/bulkhead.

tomo pauk said:
Maybe install the whole power egg from the Avia 135, ditching the retractable raditor.

What "power egg"??

Just because a plane groups the radiator and oil cooler near the engine does not mean that the whole package (including cowl) comes off with just a few bolts/connections.

The retractable radiator on the HE 100 was sort of an auxiliary cooler. The bulk of the cooling was done by the wing surfaces, and the turtle deck/vertical fin/horizontal stabilizer surfaces for the oil cooling system.

I am not certain how much of the coolant was allowed to turn to steam in the He 100 system, if any. But the cooling requirements of the Hispano engine might be different than the DB engines used in the He 100.

DerAdlerIstGelandet · Jun 7, 2013

The same usual people (both Luftwaffephiles snd Alliedofreaks - yeah you are just as bad) seem to be falling into the same old routine of snide remarks, insults and thread detracting comments. If I see one more post like thise, the offender can take it elseware. They won't be welcome here.

You all know who you are...

nuuumannn · Jun 7, 2013

The He 100 used something closer to this

The Ki-61, which the pictures in Shortround's post show, was re-engined with a radial to become the Ki-100, but as SR stated, the whole forward section of the aircraft would need redesigning. It was certainly possible, but not as simple as unbolting one engine and fitting another.

tomo pauk · Jun 7, 2013

Shortround6 said:
On something like a P-36 to P-40 the engine mounts/bearers go to about the same attachment points at the firewall/bulkhead/frame and the loads are transferred to the structure ( longerons, truss framework, whatever). The fuselage covering/outer skin bears NO structural loads and is merely an aerodynamic covering for the engine ( and router of air for various needs).
...

The He 100 used something closer to this;
...
The outer covering is used (access hatches/doors aside) AS the engine mount. a more involved engineering problem.

It is possible (most anything is possible) but is it practical. Main stress attachments have to shift from the top/upper sides to the bottom/lower sides of the fuselage at the firewall/bulkhead.

Thanks for the feedback with pics, most interesting
I'd just reiterate that other people were doing many planes' modifications, modifying the He-100 to use the engine not in the great demand for the LW might have pushed Heinkel's engineers to attempt mounting the 12Y on the He-100

...
What "power egg"??

Just because a plane groups the radiator and oil cooler near the engine does not mean that the whole package (including cowl) comes off with just a few bolts/connections.

Okay, I stand corrected re. 'power egg' terminology.

The retractable radiator on the HE 100 was sort of an auxiliary cooler. The bulk of the cooling was done by the wing surfaces, and the turtle deck/vertical fin/horizontal stabilizer surfaces for the oil cooling system.
I am not certain how much of the coolant was allowed to turn to steam in the He 100 system, if any. But the cooling requirements of the Hispano engine might be different than the DB engines used in the He 100.

The 12Y was making maybe 80 % of power the DB-601A was making, the cooling requirements should be smaller.

cimmex · Jun 7, 2013

Engine swap is not as easy as you think. Even a similar engine like the Ash 82 instead a BMW801 caused a lot of problems at the Flugwerk FW190A-8N and it took years after meiermotors presented a satisfying solution.
cimmex
Focke Wulf Fw190 Baureihe A

Shortround6 · Jun 7, 2013

Thank you for the link although I got a bit lost.

Found these pictures of the Hispano engine though;

Hispano-Suiza 12 Y

cimmex · Jun 7, 2013

I have realized also that the first link is not working but the other two should work.
cimmex

A superior German fighter

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